<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>inRange</title>
</head>

<body>
    <div>打开浏览器控制台查看结果</div>
    <script>
        const inRange = (n, start, end = null) => {
            if (end && start > end) {
                [end, start] = [start, end];
            }
            return end === null ? n >= 0 && n < start : n >= start && n < end;
        };
        console.log(inRange(3, 2, 5));
    </script>
</body>

</html>